1. Field of the Invention
The present invention relates to an authentication system for performing authentication using characteristic data read from a user.
2. Description of the Related Art
An authentication system is known in which characteristic data read from a user who wishes to pass through a gate is compared sequentially with the characteristic data of one or more registrants, and if the read data is determined to match the characteristic data of one of the registrants, the authentication is determined to be successful and the user is permitted to pass through the gate. Such authentication is known as so-called 1:N authentication, and it has been proposed to narrow the characteristic data of registrants to be compared, in order to realize high-speed 1:N authentication.
Generally, in a system which performs high-speed 1:N authentication by narrowing the characteristic data of registrants, data to be compared is first narrowed on the basis of the rough characteristic data or attributes read from a user, followed by comparison for identifying the user. Such authentication systems are proposed in Japanese Patent Laid-Open Nos. 2000-60825 and 2000-90264. An authentication system has been also proposed which preferentially selects registrants who frequently pass through a gate or users who have recently passed through a gate (see Japanese Patent Laid-Open No. 10-280755).
However, the authentication systems shown in Japanese Patent Laid-Open Nos. 2000-60825 and 2000-90264 have a problem in that a special apparatus is required for obtaining characteristic data or attributes from a user to perform the first narrowing process. Another problem is that it is necessary to prepare and register information which serves as a clue for the narrowing process, in advance for each of the users.
In such an authentication system as shown in Japanese Patent Laid-Open No. 10-280755, the narrowing process is possible only for users who have undergone authentication in the past. Therefore, there is a problem in that such an authentication system cannot be used for users who are undergoing authentication for the first time, or longer authentication time is required for users who infrequently pass through a gate or have not passed through a gate for a long time.